Effect of Nitro Orientation on Ras -Protooncogene Mutation in Liver Tumors from 7-Nitrodibenz[ a,h ]anthracene-Treated Mice

Dibenz[ a,h ]anthracene (DB[ a,h ]A) and 7-nitrodibenz[ a,h ]anthracene (7-NDB[ a,h ]A) induced liver tumors when administered to neonatal B6C3F 1 mice. For protooncogene analysis, RNA was isolated from each of the liver tumors from treated mice and reverse-transcribed into cDNA. Portions of the K- and H- ras protein coding sequences were then amplified and analyzed for DNA sequence alterations. DB[ a,h ]A-induced liver tumors had a 100% (23/23) frequency of ras -protooncogene mutation, with 83% (19/23) occurring at the first base of K- ras codon 13 and resulting in G GC M C GC transversion; the remaining 17% (4/23) of the mutations were located at the second base of H- ras codon 61. In contrast, only four of nine (44%) of 7-NDB[ a,h ]A-induced liver tumors had ras -protooncogene mutations, with two each at K- ras codon 13 and H- ras codon 61. Combined with previous observations, the results indicate that the nitro substituent perpendicular to the aromatic moiety alters the chemical-induced protooncogene activation frequency and mutational pattern in liver tumors of B6C3F 1 mice.     

The Primary Role of Apurinic Sites in Tumor Initiation

The profiles of DNA adducts determined for benzo[a]pyrene (BP), 7,12-dimethylbenz[a]anthracene (DMBA) and dibenzo[a,l]pyrene (DB[a,l]P) reveal that a majority of adducts are released from DNA by depurination. Papillomas were induced in mouse skin by several PAH, and mutations in the c-Harvey-ras oncogene were determined to investigate the relationship between DNA adducts and ras oncogene mutations. The pattern of mutations induced by each PAH correlated with the profile of depurinating adducts. DB[a,l]P and DMBA formed predominantly depurinating adenine adducts (78% and 79%, respectively) and consistently induced a CAA → CTA transversion in codon 61 of ras. In contrast, BP produced both guanine (46%) and adenine (25%) depurinating adducts and induced a GGC → GTC mutation in codon 13 of c-H-ras in 54% of tumors and a CAA → CTA mutation in codon 61 in 15% of tumors. These results support the hypothesis that mis-replication of unrepaired apurinic sites generated by loss of PAH-DNA adducts is responsible for transforming mutations leading to papillomas in mouse skin.     

Comparison of N-Heterocyclic Aromatics Dibenzo[c,g]Carbazole and Dibenz[a,j]Acridine : Metabolism,DNA Binding and Mutation

N-Heterocyclic aromatics, such as carbazole and acridine derivatives, are environmental carcinogenic pollutants. Examples of these compounds are 7H-dibenzo[c,g]carbazole (DBC) and dibenz[a,j]acridine (DBA). The ionization potential (IP) for DBC is lower than for DBA. DBC is metabolized in lung and liver by way of phenols or directly through radical cations. DBC-induced liver and lung tumors have mutations in the 61^st codon of ras. DBA is metabolized in skin by way of a diol-epoxide of DBA. DBA-induced skin tumors have mutations in 12^th, 13^th and 61^st codons of ras. In summary, the metabolic activation of DBC proceeds through different adduction pattern pathways than does DBA and leads to different ras mutational spectra.     

The Chichibabin Amination of 5-Phenylpyrimidine and Phenylpyrazine [1,2]

5-Phenylpyrimidine ( 1 ) on treatment by KNH₂/NH₃, affords a mixture of 2 amino- and 4-amino-5-phenylpyrimidine. The presence of only the anionic C-4 adduct. 4-amino-5-phenyl-1 (or 3), 4-dihydropyrimidinide was shown by ¹H- and ¹³C-NMR spectroscopy of a solution of 1 in KNH₂/NH₃. Study of the amination by use of ¹⁵N-labelled KNH₂/NH₃ convincingly shows that in the formation of the 2-amino compound a ring opening-ring closure sequence is involved. The amination of phenylpyrazine ( 11 ) into 5-amino- and 3-amino-2-phenylpyrazine has been found to occur without opening of the pyrazine ring. Examination by ¹H- and ¹³C-NMR spectroscopy of a solution of 11 in KNH₂/NH₃, reveals that at −60°C three adducts are present; i.e. 3-amino-, 5-amino- and 6-amino-2-phenyl-dihydropyrazinides, at −40°C the C-3 and C-5 adducts are formed; and at room temperature only the thermodynamically most stable C-5 adduct is present.     

Thermal switching of the actuation ability of an electroactive polymer actuator

Electroactive polymer actuators have the simple ability to be actuated by a voltage. In this study, we added a new function: the ability to be actuated by temperature. We used a bending‐electrostrictive actuator made of a polyurethane film. The polyurethane was designed to be rigid at room temperature but to be flexible at temperatures greater than 40°C because of the melting of the soft segment in the polyurethane. Therefore, the actuator showed slight bending in response to a voltage at room temperature. However, it showed significant bending at 61°C. The degree of bending at 61°C was 29 times greater than that at 13°C. Thus, the actuation ability was switched on at 61°C but switched off at 13°C. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 95: 1566–1570, 2005     

DNA Polymerase Action on Oligonucleotide Templates from Human Ha-ras Protooncogene Containing N6-Deoxyadenosine Adducts Derived from Trans Addition of (+)- and (-)-anti-Benzo[c]phenanthrene-3,4-dihydrodiol 1,2-epoxides at Codon 61

In the present work we have used a DNA polymerase assay to investigate the primer extension with T7 DNA polymerase (Sequenase 2.0) and the Klenow fragment of Escherichia coli DNA polymerase I (exo ^? KF) on chemically synthesized 21mer templates representing partial sequences of the human Ha-ras protooncogene with site-specifically positioned trans-N ⁶-dA adducts of (-)- (adduct 1) and (+)-anti-benzo[c]phenanthrene 3,4-dihydrodiol 1,2-epoxides (adduct 2) at codon 61 (CA?G; A? indicates the adducted position). With Sequenase 2.0 a complete block of primer extension opposite both adduct 1 and 2 was noted using a 10mer primer reaching the (n-1)-position of the adduct. A detailed analysis revealed that Sequenase 2.0 exclusively allowed the misincorporation of dAMP opposite both adducts. In contrast, exo ^? KF allowed a significant full-length extension of the primer beyond adduct 2, whereas this process occured only to a very minor extent for adduct 1. Correspondingly, a more intensive block of the polymerization reaction opposite adduct 1 was seen. Analysis of the arrest bands revealed that dAMP was preferentially incorporated opposite to adduct 1; also incorporation of dGMP was observed, but to a minor extent. Similarly, dAMP was also incorporated opposite to adduct 2 along with dTMP, the latter indicating a correct base pairing. Additional experiments with exo ^? KF using different 11mer primers containing each of the four nucleotides opposite the adduct suggest that the primer extension beyond adduct 2 observed with the 10mer primer is an error-free process.     

Modulation of chemical carcinogenesis in rats by alkyl lysophospholipids

The influence of 1-O-octadecyl-2-O-methyl-rac-glycero-3-phosphocholine (ET-18-OCH₃) and 1-hexadecylmercapto-2-methoxymethyl-rac-propyl-3-phosphocholine (TLP, BM41.440) on methylnitrosourea (MNU)-induced rat mammary carcinomas and of ET-18-OCH₃ on 7,12-dimethylbenzanthracene (DMBA)-induced leukemias was investigated. Both agents effectively delayed MNU-induced mammary tumor formation at high, cytotoxic dosages but TLP had no influence at low “immunomodulatory” doses. ET-18-OCH₃ also significantly protected against leukemia development in DMBA-treated Long-Evans rats.     

Reaction of thiol to diene polymer in the presence of various catalysts

The addition reaction of benzylmercaptan to diene polymer (natural rubber, and cis-1,4-polyisoprene) by various optically active catalysts such as d-camphorsulphonic acid, d-percamphoric acid, and active-amylalcoholate (sodium and barium) were carried out in benzene or anisole at room temperature to 100°C. The optically active adduct polymer was only obtained from the reaction of benzylmercaptan to natural rubber and cis-1,4-polyisoprene by active-amylalcoholate (barium), but was not obtained by the other catalysts. The [α]²⁵ value of optically active adduct polymer was ?0·1°C～?0·6°C (in benzene), and the optical rotatory dispersion curves were found to fit the simple Drude equation. The reaction of benzylmercaptan to cis-1,4-polybutadiene, various styrene-butadiene copolymers, and alternating butadiene-acrylonitrile copolymer were carried out, but the optically active adduct polymers were not obtained by these catalysts.     

阴离子型乳化剂二羟甲基丁酸的应用研究

分别选用二羟甲基丙酸(DMPA)和二羟甲基丁酸(DMBA)作为内乳化剂制备阴离子型聚氨酯乳液,测试研究了两种乳化剂对聚氨酯乳液各种性能的影响。结果表明,与DMPA相比,用DMBA作为阴离子型内乳化剂制备聚氨酯乳液具有以下特性:①DMBA的熔点为105℃,故可以在此温度下熔化/溶解在多元醇中;②用DMBA合成聚氨酯预聚体的反应时间(约50～60min)远小于用DMPA的反应时间(约150～180min);③用DMBA制备聚氨酯乳液涂膜吸水前后的拉伸强度和断裂伸长率都大于用DMPA制备的聚氨酯乳液涂膜;④以DMBA为内乳化剂制备的APU乳液粒径大而分布窄。因此,DMBA作为阴离子型乳化剂用于制备聚氨酯乳液具有良好的应用前景。     

Elongation flow studies of DNA as a function of temperature

The response of T4‐phage DNA molecules to an elongational flow field was monitored by flow‐induced birefringence as a function of temperature. The flow‐induced birefringence observed in this study was localized in the pure elongational flow area with a critical strain rate, indicating that the birefringence was attributed to a coil–stretch transition of DNA molecules. The slight decrease in the birefringence intensity with increases in temperature to 40°C was explained by a thermal‐activation process. At temperatures above 50°C, flow‐induced birefringence decreased remarkably, and no birefringence was observed at temperatures above 60°C. After the flow experiments, ambient temperature was reduced back to room temperature, and flow experiments at room temperature were performed again. Flow‐induced birefringence was recovered almost completely in samples for which the first flow measurements were made at temperatures below 53°C. Irreversible changes were observed for samples for which the first flow experiments were performed at temperatures above 55°C. The temperature dependence of UV‐absorption spectra revealed that the double‐strand DNA helix began to partially untwine at a temperature over 50°C, and duplexes became almost completely untwined at a temperature over 55°C. A comparison of electrophoresis patterns for untwined molecules showed that flow‐induced scission of DNA molecules occurred in a sample solution in flow experiments performed at 65°C, while no molecular weight reduction was observed in the sample solution at 55°C. In this article, this difference between the untwined DNA molecules is discussed on the basis of the thermally activated bond scission (TABS) model. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 1357–1365, 2002     

Characterisation of separated melamine—formaldehyde adducts (methylolmelamines) and adduct mixtures by h.p.l.c. and by n.m.r. and u.v. spectroscopy

Most of the individual methylolmelamines that occur in melamine–formaldehyde adduct mixtures have been separated by preparative high-performance liquid chromatography (h.p.l.c.) and recovered in amounts sufficient to allow their characterisation by high-field ¹H- and ¹³C-n.m.r. Particular attention has been paid to the chemical shifts of the aromatic azine carbons of the melamine nuclei. These carbon shifts are shown broadly to be in agreement with some values previously published, but additional assignments have been made. It is shown that a satisfactory quantitative analysis of the methylolmelamines in a melamine–formaldehyde adduct mixture can be carried out either by h.p.l.c. or by ¹³C-n.m.r.     

Curing temperature and humidity effects on the strength of an aluminous cement

The effects of curing temperature (21 and 60°C), time (1,7,28 days) and relative humidity (25 to 87%) on the strength and phase compositions of specimens prepared from neat Fondu paste with water/aluminous cement ratio of 0.30 were investigated. The room temperature strengths of the materials aged at 60°C, containing C₃AH₆ and AH₃, were higher than pastes cured at 21°C, containing CAH₁₀. Conversion at 60°C of the specimens aged at room temperature resulted in strengths comparable to materials isothermally cured at 60°C. The effects of these curing conditions on the high temperature strength were also investigated.     

Eicosanoid synthesis in 7,12-dimethylbenz(a)anthracene-induced mammary carcinomas in Sprague-Dawley rats fed primrose oil,menhaden oil or corn oil diet

The comparative effects of high-fat diets (20%, w/w) on eicosanoid synthesis during mammary tumor promotion in 7,12-dimethylbenz(a)anthracene (DMBA)-induced rats were studied using diets containing 20% primrose oil (PO), 20% menhaden oil (MO) or 20% corn oil (CO). Sprague-Dawley rats fed the PO or MO diet had 21% or 24% fewer adenocarcinomas, respectively, than rats fed the CO diet. Histologically (i.e., mitotic figures, inflammatory cell infiltration and necrosis), the CO-fed rats exhibited the highest frequency of changes within tumors. Plasma fatty acid composition was significantly altered by diet, reflecting the composition of the oils which were being fed. Only the plasma of PO-fed rats contained detectable levels of gamma-linolenic acid (GLA). Arachidonic acid (AA) levels were significantly higher (p<0.05) in PO-fed than in CO- or MO-fed rats. MO-fed rats had significantly higher levels of plasma palmitic acid, while palmitoleic, eicosapentaenoic (EPA) and docosahexaenoic (DHA) acids were detected only in MO-fed rats. As expected, linoleic acid (LA) and AA levels were lower (p<0.05) in the MO-fed rats than in PO- or CO-fed groups. The plasma of the CO-fed rats contained significantly higher levels of oleic acid. Eicosanoid synthesis in mammary carcinomas of rats fed the 20%-fat diets was 2–10 times higher than in mammary fat pads of control rats. The synthesis of PGE₁ and LTB₄ was significantly (p<0.05) higher in PO-fed rats than in CO-fed or MO-fed rats, although PGE values were significantly (p<0.05) higher in CO-fed rats than in Mo or PO groups. The synthesis of eicosanoids in both mammary fat pads and mammary carcinomas of MO-fed rats was lower (p<0.05) than in tissues of rats fed either CO or PO diets due to less AA precursor being fed and/or to competition between n−6 and n−3 fatty acids for cyclooxygenase and lipoxygenase. The ratios of monoenoic to dienoic eicosanoids in both mammary fat pads and mammary carcinomas were higher in the PO group than in the MO or CO groups. These results suggest that inclusion of GLA (PO feeding) or EPA and DHA (MO feeding) in the diet may decrease malignancy by altering eicosanoid profiles.     

A Metabolic Activation Mechanism of 7 H -Dibenzo[ c,g ]carbazole Via o -Quinone. Part 1: Synthesis of 7 H -Dibenzo[ c,g ]carbazole-3,4-dione and Reactions with Nucleophiles

7 H -Dibenzo[ c,g ]carbazole (DBC) is a potent carcinogen present in the environment. The metabolic activation pathway of DBC has not been completely understood. The formation of the DBC- o -quinone was proposed and the novel DBC-3,4-dione was chemically synthesized from 4-OH- or 3-OH-DBC, using the Fremy's salt at room temperature. The DBC-3,4-dione was found to react readily with model nucleophile, 2-mercaptoethanol, to afford 1-(2'-hydroxyethylthio)-DBC-3,4-dione through 1,4-Michael addition. An adduct of DBC-3,4-dione with adenine was obtained; adducts formed with other DNA bases and nucleosides were partially characterized and are under further analysis. Under the same conditions, DBC-3,4-dione with guanine did not yield an adduct. These results are encouraging for further studies on DNA binding of DBC through 3,4-dione in vitro and in vivo.     

The Protonation of Aromatic π Carbocations. The Behavior of 2-Hydroxy- and 9-Hydroxyphenalenone in Trifluoromethanesulfonic Acid

In continuation of work on the protonation of aromatic π carbocations, the behavior of 1,2-dihydroxyphenalenyl cation ( 7 ) and 1,9-dihydroxyphenalenyl cation ( 8 ) in CF₃SO₃D was investigated. The behavior of carbocation 8 was unexceptional. It underwent a facile exchange at room temperature, with H-2, H-5 and H-8 all exchanging at comparable rates. Carbocation 7 , on the other hand, exchanged at an exceptionally slow rate, even at 100°C. The order of reactivity of the various sites on 7 was found to be H-3 ≫ H-5 ⪖ H-4 ≈ H-6; H-7, H-8 and H-9 did not exchange. These unusual results are best accommodated by assuming that most, if not all, of the exchange actually occurs on 2-hydroxyphenalenone ( 9 ) which is present in very low concentration. Hückel calculations support this contention.     

Refining and Bleaching of Peanut Miscella

The effects of type of crude miscella, oil content in miscella, concentrations of caustic soda solutions, method of mixing and temperature on the refining of high f. f. a. dark coloured peanut miscellas were investigated. Very effective removal of free fatty acids and decolorisation of the peanut miscellas were achieved by treating at 45-60% oil content with 16°-20° Bé caustic soda solution at room temperature (ca. 32 ± 1° C). Good bleaching of refined miscella samples also at room temperature with commercial acid treated earth and active charcoal was possible. Refined oils had 0.02-0.06% f. f. a. with 94-99% colour removed. Successful commercial possibilities are indicated.     

硫酸钠-过氧化氢-氯化钠加合物制备新方法

以硫酸钠、氯化钠和双氧水为原料制备硫酸钠-过氧化氢-氯化钠加合物(4Na₂SO₄ •2H₂O₂•NaCl),研究了双氧水用量、反应时间、反应温度、干燥条件对产品中过氧化氢含量的影响。实验结果表明：将硫酸钠与氯化钠按加合物结构以化学计量质量比加入,30%过氧化氢稍过量,在反应温度为15～30 ℃、反应时间为60 min、干燥温度为35 ℃、干燥时间为60 min条件下,制备的加合物产品中过氧化氢质量分数可达到9.20%以上。用红外光谱对加合物产品进行了表征。将加合物产品于室温放置一个月,其稳定度达99.50%以上。     

Transverse thermoelectric multilayer generator with bismuth-substituted calcium cobaltite: Design optimization through variation of tilt angle

Sintering of Ca_2.7Bi_0.3Co₄O₉ pellets and multilayer laminates at 920 °C results in a ceramic microstructure with low density with a pronounced anisotropy. The electrical conductivity of multilayers is 56 S/cm at 400 K (perpendicular to pressing direction). The Seebeck coefficient is positive, and the power factor increases from 60 μW/(K²m) at 400 K to 200 μW/(K²m) at 900 K. The thermal conductivity (parallel to pressing direction) is 0.65 W/(mK). Transverse multilayer thermoelectric generators (TMLTEG) were fabricated by stacking layers of Ca_2.7Bi_0.3Co₄O₉ green tapes, screen-printing of AgPd stripes at various tilt angle φ relative to the heat flux direction (20°, 45°, and 65°), and co-firing at 920 °C. For φ = 65° the power output is 8 mW at ΔT = 200 K with room temperature at the cold side. FEM modelling as well as analytical calculations agree well with measurements, and the optimum tilt angle is found to be φ = 58°.     

Determination of the Petroselinic Acid in Seeds of Coriandrum sativum by Gas Liquid Chromatography as n-Butyl Esters

Oleic acid (18:1 n9), vaccenic acid (18:1 n7). and petroselinic acid (18:1 n12) can not be separated by gas chromatography (GLC) as their methylesters. But separations of their n-butyl esters are feasible. With 0.1 mol Na-tert-butanol as catalyst, dissolved in n-butanol, an extraction from the seed grist and simultaneous transbutylation of the lipids can be achieved within 20 min at room temperature. Using a capillary column (60 m DB-23, 0.25 μ, J&W, No. 122-2362), hydrogen as carrier gas and an oven temperature of 220° C, one analysis can be performed within 13 min.